Image capturing apparatus, manufacturing method thereof, and camera

ABSTRACT

A back-side illumination image capturing apparatus includes a semiconductor substrate having a first surface for receiving incident light and a second surface located on the opposite side as the first surface, and including a photoelectric conversion portion, and a gate electrode disposed above the second surface. The apparatus further includes a first insulating layer disposed above the second surface of the semiconductor substrate, an interlayer insulation film disposed on the first insulating layer, a contact plug connected to the gate electrode, and a light-cutting portion for cutting light, of the incident light, that has passed through the photoelectric conversion portion. The light-cutting portion passes through at least part of the interlayer insulation film. The first insulating layer is located between the light-cutting portion and the semiconductor substrate.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to image capturing apparatuses,manufacturing methods thereof, and cameras.

Description of the Related Art

A photoelectric conversion portion is typically thinner in back-sideillumination image capturing apparatuses than in front-side illuminationimage capturing apparatuses, and thus light incident on the imagecapturing apparatus can be insufficiently absorbed by the photoelectricconversion portion, resulting in some of that light passing through thephotoelectric conversion portion. Mixing of colors can occur betweenpixels in the case where the light that has passed through thephotoelectric conversion portion is reflected by a wiring layer or thelike and reaches the photoelectric conversion portions of other pixels.In order to prevent the mixture of colors, Japanese Patent Laid-Open No.2010-177704 proposes a structure in which a cylindrical metal layer isdisposed above the photoelectric conversion portion with a gateinsulation film provided therebetween. Light that has passed through thephotoelectric conversion portion and advanced to an inner side of thecylindrical metal layer is reflected by the side surfaces of the metallayer.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a back-sideillumination image capturing apparatus comprises a semiconductorsubstrate having a first surface for receiving incident light and asecond surface located on the opposite side as the first surface, andincluding a photoelectric conversion portion, and a gate electrodedisposed above the second surface, a first insulating layer disposedabove the second surface of the semiconductor substrate, an interlayerinsulation film disposed on the first insulating layer, a contact plugconnected to the gate electrode, and a light-cutting portion for cuttinglight, of the incident light, that has passed through the photoelectricconversion portion. The light-cutting portion passes through at leastpart of the interlayer insulation film. The first insulating layer islocated between the light-cutting portion and the semiconductorsubstrate.

According to another aspect of the present invention, a back-sideillumination image capturing apparatus comprises a semiconductorsubstrate having a first surface for receiving incident light and asecond surface located on the opposite side as the first surface, andincluding a photoelectric conversion portion, and a gate electrodelocated above the second surface, an interlayer insulation film disposedabove the second surface of the semiconductor substrate, a contact plugconnected to the gate electrode, and a light-cutting portion for cuttinglight, of the incident light, that has passed through the photoelectricconversion portion. Part of the interlayer insulation film is locatedbetween the light-cutting portion and the semiconductor substrate.

According to yet another aspect of the present invention, a method formanufacturing a back-side illumination image capturing apparatus isprovided. The image capturing apparatus includes a semiconductorsubstrate having a first surface for receiving incident light and asecond surface located on the opposite side as the first surface, andincluding a photoelectric conversion portion, and a gate electrodelocated above the second surface, a contact plug connected to the gateelectrode, and a light-cutting portion for cutting light, of theincident light, that has passed through the photoelectric conversionportion. The method comprises forming a first insulating layer above thesecond surface of the semiconductor substrate and forming an interlayerinsulation film above the first insulating layer, forming a firstopening for forming the contact plug by etching away part of theinterlayer insulation film and part of the first insulating layer, andforming a second opening for forming the light-cutting portion byetching away another part of the interlayer insulation film. In the stepof forming the first opening, the first opening reaches the gateelectrode. In the step of forming the second opening, at least part ofthe first insulating layer is left between the second opening and thesemiconductor substrate.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams illustrating an example of the structure ofan image capturing apparatus according to some embodiments.

FIGS. 2A to 3D are diagrams illustrating an example of a method formanufacturing the image capturing apparatus shown in FIGS. 1A and 1B.

FIGS. 4A and 4B are diagrams illustrating a variation on the imagecapturing apparatus shown in FIGS. 1A and 1B.

FIGS. 5A and 5B are diagrams illustrating a variation on the imagecapturing apparatus shown in FIGS. 1A and 1B.

FIGS. 6A and 6B are diagrams illustrating a variation on the imagecapturing apparatus shown in FIGS. 1A and 1B.

FIGS. 7A and 7B are diagrams illustrating a variation on the imagecapturing apparatus shown in FIGS. 1A and 1B.

FIGS. 8A and 8B are diagrams illustrating an example of the structure ofan image capturing apparatus according to some other embodiments.

FIGS. 9A to 9D are diagrams illustrating an example of a method formanufacturing the image capturing apparatus shown in FIGS. 8A and 8B.

FIGS. 10A and 10B are diagrams illustrating an example of the structureof an image capturing apparatus according to some other embodiments.

FIGS. 11A to 12D are diagrams illustrating an example of a method formanufacturing the image capturing apparatus shown in FIGS. 10A and 10B.

FIGS. 13A and 13B are diagrams illustrating an example of the structureof an image capturing apparatus according to some other embodiments.

FIG. 14 is a diagram illustrating an example of a method formanufacturing the image capturing apparatus shown in FIGS. 13A and 13B.

DESCRIPTION OF THE EMBODIMENTS

Several embodiments will be described hereinafter with reference to theappended drawings. Elements that are the same throughout the embodimentswill be assigned the same reference numerals, and redundant descriptionsthereof will be omitted. Note that various embodiments can be altered orcombined as appropriate.

Japanese Patent Laid-Open No. 2010-177704 discloses forming openings inan interlayer insulation film provided upon a gate insulation film andembedding the metal layer in the openings in order to achieve theaforementioned configuration. However, this document does not discuss aspecific method for forming the openings in the interlayer insulationfilm.

The inventors of the present invention realized that openings can beformed in an interlayer insulation film through etching. Furthermore,the inventors of the present invention realized that the followingissues can arise when forming openings through etching. For example, asimage capturing apparatuses have become smaller, gate insulation filmshave become thinner. Accordingly, there is a risk that a gate insulationfilm will fail to function as an etching stopper layer, resulting in thephotoelectric conversion portion located below the gate insulation filmbeing exposed during etching carried out to form the stated openings.When the photoelectric conversion portion is exposed, metal from themetal layer can contaminate the photoelectric conversion portion,resulting in dark current. This problem is particularly prevalent incases such as where the interlayer insulation film and the gateinsulation film are formed of the same material and there is nodifference or only a small difference between the etching rates of thetwo films. Accordingly, some embodiments of the present inventionprovide techniques for reducing damage to a photoelectric conversionportion caused when etching an interlayer insulation film.

The structure of an image capturing apparatus 100 according to someembodiments will be described with reference to FIGS. 1A and 1B. FIG. 1Ais a plan view illustrating part of the image capturing apparatus 100,whereas FIG. 1B illustrates a cross-sectional view taken along the A-Aline in FIG. 1A. Some constituent elements have been omitted from theplan view in FIG. 1A in order to make the illustrations clearer. Asindicated in FIG. 1B, the image capturing apparatus 100 is a back-sideillumination image capturing apparatus 100, and the image capturingapparatus 100 can receive incident light from below, in the depiction inFIG. 1B, and convert that light into a signal. However, some embodimentsare not limited to the configuration of the image capturing apparatusshown in FIGS. 1A and 1B, and can be applied in any configuration aslong as the image capturing apparatus is a back-side illumination type.

The image capturing apparatus 100 includes a plurality of pixelsdisposed in array form, and four of those pixels PX are illustrated inFIG. 1A. Each pixel PX can include an N-type semiconductor region 101formed in a semiconductor substrate SUB, an N-type semiconductor region102 having a higher impurity concentration than the semiconductor region101, and a P-type semiconductor region 103 formed on a surface of thesemiconductor substrate SUB. Furthermore, a P-type semiconductor region104 can be provided on the surface of the semiconductor substrate SUB ona light-incident side thereof, and the semiconductor regions 101 to 104can function as a photoelectric conversion portion. For example, thesemiconductor regions 101 to 104 can configure a photodiode. Thesemiconductor region 102 can function as an accumulation region thataccumulates electrons generated by the photoelectric conversion portion.

The semiconductor substrate SUB includes a floating diffusion FD, whichis an N-type semiconductor region, in the center of the four pixels PX.The floating diffusion FD is shared by the four pixels PX. Each pixel PXhas a transfer gate 106 that is positioned so as to cover a regionbetween the floating diffusion FD and the semiconductor region 102, anda P-type barrier region 105 is provided below the transfer gate 106. Thetransfer gate 106 is formed of polysilicon, for example, and configurespart of a transfer transistor that transfers a charge.

In addition to the photoelectric conversion portion, each pixel PXincludes a plurality of transistors, and the right side of FIG. 1Billustrates the cross-sectional structure of a single transistor. Thistransistor can be a reset transistor for resetting the photoelectricconversion portion, an amplifying transistor for amplifying thepotential of the floating diffusion FD, a readout transistor for readingout a pixel signal to a signal line, or the like. The transistor canhave P-type semiconductor regions 107 and 108 formed on thesemiconductor substrate SUB and a gate 109 formed in a position so thatthe gate 109 covers a region between the semiconductor regions 107 and108. Although not illustrated, a gate insulation film is disposed belowthe transfer gate 106 and the gate 109. The semiconductor substrate SUBcan have an element isolation region ISO such as shallow trenchisolation (STI), a P-type channel stop region 110, and a P-typeisolation region 111 in the periphery of the transistors, thephotoelectric conversion portion, and so on. The solid line BD in FIG.1A illustrates a border between the photoelectric conversion portions ofthe pixels PX and the element isolation region ISO disposed in theperiphery thereof.

The image capturing apparatus 100 can further include an antireflectionlayer 112, an interlayer insulation film 113, a planarizing layer 114, acolor filter CF, and microlenses ML, in that order on the light-incidentside of the semiconductor substrate SUB (the bottom, in FIG. 1B). Alight-shielding layer 115 is formed upon the planarizing layer 114. Thelight-shielding layer 115 can have a grid shape that covers the borderswith adjacent pixels PX.

The image capturing apparatus 100 can further include an insulatinglayer 116 (a first insulating layer), an interlayer insulation film 117,and a supporting substrate 118, in that order on the opposite side asthe light-incident side of the semiconductor substrate SUB (the top, inFIG. 1B). The insulating layer 116 may contain a different material thanthe interlayer insulation film 117. The insulating layer 116 can have alayered structure including, for example, a silicon nitride film and asilicon oxide film serving as layers. The interlayer insulation film117, meanwhile, can be formed of, for example, silicon oxide. As will bedescribed later, the insulating layer 116 functions as an etchingstopper layer when etching the interlayer insulation film 117. The imagecapturing apparatus 100 can include a plurality of wiring layers withinthe interlayer insulation film 117. In other words, the interlayerinsulation film 117 is an insulation film disposed between the wiringlayers and the semiconductor substrate SUB. Each wiring layer caninclude a wiring pattern 119 formed of aluminum, copper, or the like,and a barrier metal 120 formed of TiN/Ti or the like. The semiconductorregions 107 and 108 that configure part of the transistor are connectedto the wiring layers by a contact plug 121 formed of tungsten or thelike. In addition, the transfer gate 106, the gate 109, and so on areconnected to the wiring layers by a contact plug 122 formed of tungstenor the like. The contact plugs 121 and 122 pass through the interlayerinsulation film 117 and the insulating layer 116.

The image capturing apparatus 100 can further include a light-cuttingportion 123 and a reflective layer 124 within the interlayer insulationfilm 117. The light-cutting portion 123 is formed of a metal such astungsten, copper, or the like, and prevents light that has passedthrough the photoelectric conversion portion from reaching thephotoelectric conversion portions of other pixels by cutting that light.In this embodiment, the light-cutting portion 123 is configured of amaterial having a lower transmissibility than the interlayer insulationfilm 117. However, it is not necessary for all of the light to be cut bythe light-cutting portion 123. The reflective layer 124 is formed of ametal such as aluminum, copper, or the like, and returns light that haspassed through the photoelectric conversion portion to the photoelectricconversion portion by reflecting that light. In some embodiments, thelight-cutting portion 123 is cylindrical in shape, and the reflectivelayer 124 is formed in a shape/position so as to serve as a cover forthe cylindrical light-cutting portion 123. In other words, thereflective layer 124 has a pillar-like shape, and an upper surface ofthe light-cutting portion 123 makes contact with a base surface of thereflective layer 124. The reflective layer 124 may configure part of thewiring pattern 119. In other words, the configuration may be such thatwhen the image capturing apparatus 100 operates, a current flows throughthe reflective layer 124, a voltage is applied to the reflective layer124, or the like. Although the light-cutting portion 123 passes throughthe interlayer insulation film 117, the light-cutting portion 123 doesnot pass through the insulating layer 116. In other words, theinsulating layer 116 is disposed between the light-cutting portion 123and the semiconductor substrate SUB. The interlayer insulation film 117may include a plurality of insulating layers. Here, the light-cuttingportion 123 may pass through some of the insulating layers in theinterlayer insulation film 117, as shown in FIG. 1B, or may pass throughthe entirety of the interlayer insulation film 117. Furthermore, thelight-cutting portion 123 is not limited to a cylindrical shape. Forexample, a plurality of light-cutting portions 123 may be disposedintermittently so as to enclose a single photoelectric conversionportion.

An example of a method for manufacturing the image capturing apparatus100 shown in FIGS. 1A and 1B will now be described with reference toFIGS. 2A to 2D and 3A to 3D. FIGS. 2A to 2D and 3A to 3D arecross-sectional views from the same position as in FIG. 1B. First, asshown in FIG. 2A, the semiconductor substrate SUB, formed having thestructure illustrated in FIGS. 1A and 1B, is prepared. The semiconductorsubstrate SUB can be formed using an existing method, and thusdescriptions thereof will be omitted. The semiconductor substrate SUBhas a front surface FS (a first surface) and a back surface BS (a secondsurface) on the opposite side thereof (that is, on the opposite side asthe first surface). Light incident on the image capturing apparatus 100is incident on the photoelectric conversion portion from the backsurface BS of the semiconductor substrate SUB.

Next, as shown in FIG. 2B, the transfer gate 106 and the gate 109 areformed using polysilicon or the like. Although not illustrated, a gateinsulation film is formed below the transfer gate 106 and the gate 109.Thereafter, the insulating layer 116 is deposited on the front surfaceFS (on the second surface) of the semiconductor substrate SUB over thetransfer gate 106 and the gate 109 through plasma CVD. The insulatinglayer 116 can have a layered structure including, for example, a siliconnitride film and a silicon oxide film serving as layers. The insulatinglayer 116 may be formed at a thickness that enables the insulating layer116 to function as an antireflection layer. Thereafter, the interlayerinsulation film 117 is formed by depositing silicon oxide on theinsulating layer 116 through plasma CVD, and the upper surface of theinterlayer insulation film 117 is then planarized through CMP.

Next, as shown in FIG. 2C, a mask pattern 201 is formed on theinterlayer insulation film 117. The mask pattern 201 exposes positionsin which contact plugs connected to circuit elements formed in thesemiconductor substrate SUB, such as the contact plugs 121 and 122, areto be formed, and covers the other areas. Etching is then carried outover the mask pattern 201, forming openings 202 and 203 by removing partof the interlayer insulation film 117 and part of the insulating layer116. The opening 202 reaches the semiconductor region 108, and part ofthe upper surface of the semiconductor region 108 is exposed through theopening 202. This exposed area serves as a connection surface with thecontact plug 121. The opening 203 (a first opening) reaches the transfergate 106, and part of the upper surface of the transfer gate 106 isexposed through the opening 203. This exposed area serves as aconnection surface with the contact plug 122. As a first step, etchingmay be carried out using a method that is highly selective of theinterlayer insulation film 117 over the insulating layer 116 (that is,that etches the interlayer insulation film 117 at a higher etchingrate), and then, as a second step, the etching may be carried out underdifferent conditions.

Next, as shown in FIG. 2D, the mask pattern 201 is removed, and a maskpattern 204 is formed on the interlayer insulation film 117. The maskpattern 204 exposes positions where the light-cutting portion 123 shownin FIGS. 1A and 1B is to be formed, and covers the other areas. Etchingis then carried out over the mask pattern 204, forming an opening 205 byremoving part of the interlayer insulation film 117. Although theopening 205 (a second opening) reaches the insulating layer 116, theinsulating layer 116 functions as an etching stopper layer during thisetching, and thus the opening 205 does not reach the semiconductorsubstrate SUB. For example, if, in the etching carried out at this time,the etching rate of the insulating layer 116 is higher than the etchingrate of the interlayer insulation film 117, the insulating layer 116 canfunction as an etching stopper layer. Accordingly, a combination of anetching method that achieves this etching rate relationship andmaterials for the interlayer insulation film 117 and the insulatinglayer 116 may be selected as appropriate. Alternatively, using aninsulation film that is thicker than the gate insulation film as theinsulating layer 116 can enable the insulating layer 116 to function asan etching stopper layer. In this case, the etching method, the etchingrates, and so on are not particularly limited.

Next, as shown in FIG. 3A, tungsten is embedded in the openings 202,203, and 205 after the mask pattern 204 has been removed. As a result,the contact plug 121 is formed in the opening 202, the contact plug 122is formed an opening 203, and the light-cutting portion 123 is formed inthe opening 205.

Next, as shown in FIG. 3B, the barrier metal 120 is deposited on theinterlayer insulation film 117, the contact plugs 121 and 122, and thelight-cutting portion 123, and the barrier metal 120 located in aposition where the reflective layer 124 is to be formed is etched away.Then, as shown in FIG. 3C, a metal layer 301 is formed of aluminum orthe like on the barrier metal 120 and on the region from which thebarrier metal 120 has been removed. Next, in FIG. 3D, the wiring pattern119 in the first layer and reflective layer 124 are formed by etchingthe metal layer 301 and the barrier metal 120. In this manner, thereflective layer 124 is formed through patterning in parallel with theprocess of patterning the wiring pattern 119, thus reducing the numberof processes. Thereafter, the other constituent elements are formedusing existing methods, and the image capturing apparatus 100 shown inFIGS. 1A and 1B is completed thus.

In the method for manufacturing the image capturing apparatus 100described above, the interlayer insulation film 117 is etched using theinsulating layer 116 as an etching stopper layer, and thus damage to thephotoelectric conversion portion during the manufacture of the imagecapturing apparatus 100 can be reduced. The insulating layer 116 is adifferent layer than the gate insulation film. Alternatively, theinsulating layer 116 contains a different material than the interlayerinsulation film 117. Because the insulating layer 116, which is separatefrom the gate insulation film, is provided as the etching stopper layer,the image capturing apparatus 100 can be manufactured using a methodthat reduces damage to the photoelectric conversion portion. In themanufacturing method described above, a metal is embedded into theopenings 202, 203, and 205 simultaneously in order to produce thecontact plugs 121 and 122 and the light-cutting portion 123,respectively. This method embeds the metal in a single process, and thusthe number of processes can be reduced. However, after producing thecontact plugs 121 and 122 by embedding the metal in the openings 202 and203 in the state shown in FIG. 2C, the process may then advance to thestate shown in FIG. 2D, and the opening 205 may be formed. This methodcan further reduce damage to the semiconductor substrate SUB. Inaddition, in the image capturing apparatus 100, part of thelight-cutting portion 123 is disposed on the transfer gate 106 andanother part of the light-cutting portion 123 is disposed on thephotoelectric conversion portion. According to this configuration, amixture of colors caused by light passing through the vicinity of thetransfer gate 106 can be reduced. In this configuration, damage to thephotoelectric conversion portion can be further reduced by forming theinsulating layer 116 so as to be a continuous layer spanning from abovethe photoelectric conversion portion to above the transfer gate 106.

Next, variations on the image capturing apparatus 100 shown in FIGS. 1Aand 1B will be described with reference to FIGS. 4A to 7B. An imagecapturing apparatus 400 shown in FIGS. 4A and 4B differs from the imagecapturing apparatus 100 shown in FIGS. 1A and 1B in terms of thepositional relationship between the photoelectric conversion portion andthe light-cutting portion 123. The light-cutting portion 123 is disposedabove the photoelectric conversion portion in the image capturingapparatus 100, as indicated by the solid line BD. This arrangement makesit possible to reduce the intervals between adjacent photoelectricconversion portions. On the other hand, part of the light-cuttingportion 123 is disposed above the element isolation region ISO in theimage capturing apparatus 400, as indicated by the solid line BD. Thisarrangement makes it possible to cut light that has passed through thephotoelectric conversion portion across a wider range. The imagecapturing apparatus 400 can be manufactured by altering the method formanufacturing the image capturing apparatus 100 described above so as tochange the position of the openings in the mask pattern 204 illustratedin FIG. 2D.

An image capturing apparatus 500 shown in FIGS. 5A and 5B differs fromthe image capturing apparatus 100 shown in FIGS. 1A and 1B in terms ofthe shape of the light-cutting portion 123. The light-cutting portion123 of the image capturing apparatus 100 has a cylindrical shapeextending away from the front surface FS of the semiconductor substrateSUB. On the other hand, the light-cutting portion 123 of the imagecapturing apparatus 500 has a pillar shape extending away from the frontsurface FS of the semiconductor substrate SUB. As a result of thisshape, the light-cutting portion 123 also functions as a reflectivelayer, returning light that has passed through the photoelectricconversion portion back toward the photoelectric conversion portion byreflecting that light near the photoelectric conversion portion. It isnot necessary for all of the light to be reflected by the light-cuttingportion 123. The image capturing apparatus 500 can be manufactured byaltering the method for manufacturing the image capturing apparatus 100described above so as to change the shape of the openings in the maskpattern 204 illustrated in FIG. 2D. It is possible to combine the shapeof the light-cutting portion 123 in the image capturing apparatus 500with the configuration of the image capturing apparatus 400.

An image capturing apparatus 600 shown in FIGS. 6A and 6B differs fromthe image capturing apparatus 100 shown in FIGS. 1A and 1B in that thereflective layer 124 is not provided. By having the reflective layer124, the image capturing apparatus 100 can return light that has passedthrough the photoelectric conversion portion back toward thephotoelectric conversion portion, thus increasing the sensitivity of thephotoelectric conversion portion. On the other hand, the image capturingapparatus 600 does not have a reflective layer in the first-layer wiringlayer, thus increasing the freedom with which the wiring pattern 119 canbe formed in the first-layer wiring layer. The image capturing apparatus600 also includes the light-cutting portion 123, and thus the amount oflight passing through the photoelectric conversion portion that reachesthe photoelectric conversion portions of other pixels can be reduced.The image capturing apparatus 600 can be manufactured by altering themethod for manufacturing the image capturing apparatus 100 describedabove so as to remove the reflective layer 124 by etching the metallayer 301 illustrated in FIG. 3D. The configuration of the imagecapturing apparatus 600, which does not have the reflective layer 124,can be combined with the configurations of either of the image capturingapparatuses 400 and 500.

An image capturing apparatus 700 shown in FIGS. 7A and 7B differs fromthe image capturing apparatus 100 shown in FIGS. 1A and 1B in that alight-cutting portion 701 formed by an air gap is provided instead ofthe light-cutting portion 123 formed of a metal such as tungsten. Thelight-cutting portion 701 is also cylindrical in shape, and siliconoxide that forms the interlayer insulation film 117 is present on theinner side of the light-cutting portion 701. The refractive index ofsilicon oxide is higher than the refractive index of the air gap(atmospheric air, or a gaseous body in which a gas intermixes with theatmospheric air during manufacture), and thus light that advances to theinner side of the light-cutting portion 701 is reflected at the borderbetween the light-cutting portion 701 and the interlayer insulation film117. Accordingly, in this variation, there is no particular limit on therelationship between the transmissibility of the light-cutting portion701 and the transmissibility of the interlayer insulation film 117. Theimage capturing apparatus 700 can be manufactured by altering the methodfor manufacturing the image capturing apparatus 100 described above sothat a metal such as tungsten is not embedded in the opening 205 shownin FIG. 3A, leaving the opening as-is. The light-cutting portion 701 ofthe image capturing apparatus 700 can be combined with theconfigurations of either of the image capturing apparatuses 400 and 500.

Next, the structure of an image capturing apparatus 800 according tosome other embodiments will be described with reference to FIGS. 8A and8B. FIG. 8A is a plan view illustrating part of the image capturingapparatus 800, whereas FIG. 8B illustrates a cross-sectional view takenalong the A-A line in FIG. 8A. Some constituent elements have beenomitted from the plan view in FIG. 8A in order to make the illustrationsclearer. The image capturing apparatus 800 differs from the imagecapturing apparatus 100 shown in FIGS. 1A and 1B in that an insulatinglayer 801 (a second insulating layer) that functions as an etchingstopper layer is further provided. Descriptions of content alreadydescribed in the aforementioned embodiment will therefore not berepeated. The insulating layer 801 is disposed in a position where thelight-cutting portion 123 is to be formed, and is not disposed inpositions where the contact plugs 121 and 122 are to be formed.

An example of a method for manufacturing the image capturing apparatus800 shown in FIGS. 8A and 8B will now be described with reference toFIGS. 9A to 9D. FIGS. 9A to 9D are cross-sectional views from the sameposition as in FIG. 8B. First, the semiconductor substrate SUB indicatedin FIG. 9A is prepared, in the same manner as the step of themanufacturing method illustrated in FIG. 2A. Next, as shown in FIG. 9B,the transfer gate 106, the gate 109, and the insulating layer 116 areformed, in the same manner as the step of the manufacturing methodillustrated in FIG. 2B. Thereafter, the insulating layer 801 isdeposited on the insulating layer 116 through plasma CVD. The insulatinglayer 801 can have a layered structure including, for example, a siliconnitride film and a silicon oxide film serving as layers.

Next, as shown in FIG. 9C, part of the insulating layer 801 is removedso that the insulating layer 801 remains in the position where thelight-cutting portion 123 is to be formed but does not remain in thepositions where the contact plugs 121 and 122 are to be formed.Thereafter, the interlayer insulation film 117 is formed by depositingsilicon oxide on the insulating layers 116 and 801 through plasma CVD,and the upper surface of the interlayer insulation film 117 is thenplanarized through CMP.

Next, as shown in FIG. 9D, a mask pattern 901 is formed on theinterlayer insulation film 117 so as to expose positions where thecontact plugs 121 and 122 and the light-cutting portion 123 are to beformed and cover the other parts of the interlayer insulation film 117.Etching is then carried out over the mask pattern 901, removing part ofthe interlayer insulation film 117 as a result. This etching uses anetchant gas for removing the silicon oxide that configures theinterlayer insulation film 117. This etching is stopped by the siliconnitride film contained in the insulating layer 116 at the positionswhere the contact plugs 121 and 122 are to be formed. In other words,the insulating layer 116 functions as an etching stopper layer at thesepositions. The etching is also stopped by the silicon nitride filmcontained in the insulating layer 801 at the position where thelight-cutting portion 123 is to be formed. In other words, theinsulating layer 801 functions as an etching stopper layer at thesepositions.

After this, etching is carried out over the same mask pattern 901,removing part of the silicon nitride film contained in the insulatinglayers 801 and 116 as a result. Through this, the openings 202 and 203that expose the semiconductor region 108 and the transfer gate 106 areformed at the positions where the contact plugs 121 and 122 are to beformed. On the other hand, the etching is stopped by the silicon oxidefilm contained in the insulating layer 116 at the position where thelight-cutting portion 123 is to be formed. Accordingly, the insulatinglayer 116 functions as an etching stopper layer at the position wherethe light-cutting portion 123 is to be formed, and thus damage to thephotoelectric conversion portion caused by the etching is reduced. Thesteps that follow thereafter are the same as the steps described withreference to FIGS. 3A and on, and thus redundant descriptions thereofwill be omitted.

The image capturing apparatus 800 can achieve the same effects as thosedescribed with reference to the image capturing apparatus 100.Furthermore, the various variations on the aforementioned imagecapturing apparatus 100 can be applied to the image capturing apparatus800 as well.

The structure of an image capturing apparatus 1000 according to someother embodiments will now be described with reference to FIGS. 10A and10B. FIG. 10A is a plan view illustrating part of the image capturingapparatus 1000, whereas FIG. 10B illustrates a cross-sectional viewtaken along the A-A line in FIG. 10A. Some constituent elements havebeen omitted from the plan view in FIG. 10A in order to make theillustrations clearer. As indicated in FIG. 10B, the image capturingapparatus 1000 is a back-side illumination image capturing apparatus1000, and the image capturing apparatus 1000 can receive incident lightfrom below, in the depiction in FIG. 10B, and convert that light into asignal. However, some embodiments are not limited to the configurationof the image capturing apparatus shown in FIGS. 10A and 10B, and can beapplied in any configuration as long as the image capturing apparatus isa back-side illumination type. The image capturing apparatus 1000differs from the image capturing apparatus 100 in that a light-cuttingportion 123′ is provided instead of the light-cutting portion 123. Theother configurations may be the same and thus redundant descriptionswill be omitted. The light-cutting portion 123′ does not pass throughthe interlayer insulation film 117, and thus does not reach theinsulating layer 116 located below the interlayer insulation film 117.

An example of a method for manufacturing the image capturing apparatus1000 shown in FIGS. 10A and 10B will now be described with reference toFIGS. 11A to 11D and 12A to 12D. FIGS. 11A to 11D and 12A to 12D arecross-sectional views from the same position as in FIG. 10B. The stepsshown in FIGS. 11A to 11C are the same as the steps shown in FIGS. 2A to2C, and thus redundant descriptions thereof will be omitted.

Next, as shown in FIG. 11D, the mask pattern 201 is removed, and themask pattern 204 is formed on the interlayer insulation film 117. Themask pattern 204 exposes positions where the light-cutting portion 123′shown in FIGS. 10A and 10B is to be formed, and covers the other areas.Etching is then carried out over the mask pattern 204, forming theopening 205 by removing part of the interlayer insulation film 117. Theetching time is adjusted based on data obtained in advance throughsimulations, experimentation, or the like so that the opening 205 (thesecond opening) does not reach the insulating layer 116 during thisetching. The etching is stopped before the opening 205 passes throughthe interlayer insulation film 117 by carrying out the etching only forthe adjusted time. In this manner, the formation of the openings 202 and203 for the contact plugs and the formation of the opening 205 for thelight-cutting portion are carried out through separate etchingoperations having mutually different etching times. Alternatively, inthe case where the etching is carried out for the same amount of time,the etching conditions may be altered so that the etching rate changes.For example, in the case where dry etching such as reactive ion etching(RIE) is performed, the etching rate can be altered by changing theplasma energy.

The steps shown in FIGS. 12A to 12D are the same as the steps shown inFIGS. 3A to 3D, and thus redundant descriptions thereof will be omitted.However, the light-cutting portion 123′ is formed in these steps insteadof the light-cutting portion 123.

According to the method for manufacturing the image capturing apparatus1000 described above, etching for forming the opening used to form thelight-cutting portion 123′ is carried out so that the opening does notpass through the interlayer insulation film 117, and thus damage to thephotoelectric conversion portion while manufacturing the image capturingapparatus 1000 can be reduced. In the manufacturing method describedabove, a metal is embedded into the openings 202, 203, and 205simultaneously in order to produce the contact plugs 121 and 122 and thelight-cutting portion 123′, respectively. This method embeds the metalin a single process, and thus the number of processes can be reduced.However, after producing the contact plugs 121 and 122 by embedding themetal in the openings 202 and 203 in the state shown in FIG. 11C, theprocess may then advance to the state shown in FIG. 11D, and the opening205 may then be formed. This method can further reduce damage to thesemiconductor substrate SUB. Furthermore, the various variations on theaforementioned image capturing apparatus 100 can be applied to the imagecapturing apparatus 1000 as well.

Next, the structure of an image capturing apparatus 1300 according tosome other embodiments will be described with reference to FIGS. 13A and13B. FIG. 13A is a plan view illustrating part of the image capturingapparatus 1300, whereas FIG. 13B illustrates a cross-sectional viewtaken along the A-A line in FIG. 13A. Some constituent elements havebeen omitted from the plan view in FIG. 13A in order to make theillustrations clearer. The image capturing apparatus 1300 differs fromthe image capturing apparatus 1000 shown in FIG. 10 in that thelight-cutting portion 123′ is narrower than the contact plugs 121 and122. Accordingly, redundant descriptions will not be repeated.

An example of a method for manufacturing the image capturing apparatus1300 shown in FIGS. 13A and 13B will now be described with reference toFIG. 14. FIG. 14 is a cross-sectional view from the same position as inFIG. 13B. First, the structure illustrated in FIG. 2B is prepared usingthe same manufacturing method as described above. Next, as shown in FIG.14, a mask pattern 1401 is formed on the interlayer insulation film 117so as to expose positions where the contact plugs 121 and 122 and thelight-cutting portion 123′ are to be formed and cover the other parts ofthe interlayer insulation film 117. The opening in the mask pattern 1401that exposes the position where the light-cutting portion 123′ is to beformed is narrower than the openings in the mask pattern 1401 thatexpose the positions where the contact plugs 121 and 122 are to beformed. Etching is then carried out over the mask pattern 1401, removingpart of the interlayer insulation film 117 as a result. During thisetching, the etching rate is lower the narrower the openings in the maskpattern 1401 are, and thus the opening 205 does not pass through theinterlayer insulation film 117 even if the openings 202 and 203 reachthe semiconductor region 108, the transfer gate 106, and the like as aresult of the etching. The steps that follow thereafter are the same asthe steps described with reference to FIG. 3A and on, and thus redundantdescriptions thereof will be omitted.

The image capturing apparatus 1300 can achieve the same effects as thosedescribed with reference to the image capturing apparatus 1000.Furthermore, the various variations on the aforementioned imagecapturing apparatus 100 can be applied to the image capturing apparatus1300 as well. For example, in the case where a pillar-shapedlight-cutting portion is employed as in the image capturing apparatus500 shown in FIGS. 5A and 5B, a plurality of long, narrow pillar-shapedlight-cutting portions may be formed in order to accommodate a reducedwidth in the mask pattern.

Next, an example of a camera that incorporates the image capturingapparatuses according to the aforementioned embodiments will bedescribed as a working example of the image capturing apparatuses. Theconcept of a camera includes not only a device whose primary function iscapturing images, but also a device that has an auxiliary imagecapturing function (for example, personal computers, mobile terminals,and so on). The camera includes the image capturing apparatus accordingto the present invention as described in the aforementioned embodiments,and a signal processing unit that processes signals outputted from theimage capturing apparatus. This signal processing unit can include, forexample, an A/D converter and a processor that processes digital dataoutputted from the A/D converter.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2012-233301 filed Oct. 22, 2012 and 2012-233300 filed Oct. 22, 2012,which are hereby incorporated by reference herein in their entirety.

1. A back-side illumination image capturing apparatus comprising: asemiconductor substrate having a first surface for receiving incidentlight and a second surface located on the opposite side as the firstsurface, and including a photoelectric conversion portion, and a gateelectrode disposed above the second surface; a first insulating layerdisposed above the second surface of the semiconductor substrate; aninterlayer insulation film disposed on the first insulating layer; acontact plug connected to the gate electrode; and a light-cuttingportion for cutting light, of the incident light, that has passedthrough the photoelectric conversion portion, wherein the light-cuttingportion passes through at least part of the interlayer insulation film,and the first insulating layer is located between the light-cuttingportion and the semiconductor substrate.
 2. The image capturingapparatus according to claim 1, further comprising: a second insulatinglayer, disposed between the first insulating layer and the interlayerinsulation film, through which the light-cutting portion passes.
 3. Theimage capturing apparatus according to claim 1, wherein part of thelight-cutting portion is located over the gate electrode; and the firstinsulating layer is located between the part of the light-cuttingportion and the gate electrode.
 4. The image capturing apparatusaccording to claim 1, wherein the first insulating layer contains adifferent material than a gate insulation film under the gate electrode.5. The image capturing apparatus according to claim 1, wherein thelight-cutting portion reflects the light that has passed through thephotoelectric conversion portion. 6.-20. (canceled)
 21. A cameracomprising: a back-side illumination image capturing apparatus; and asignal processing unit that processes a signal from the image capturingapparatus, wherein the back-side illumination image capturing apparatuscomprises: a semiconductor substrate having a first surface forreceiving incident light and a second surface located on the oppositeside as the first surface, and including a photoelectric conversionportion, and a gate electrode disposed above the second surface; a firstinsulating layer disposed above the second surface of the semiconductorsubstrate; an interlayer insulation film disposed on the firstinsulating layer; a contact plug connected to the gate electrode; and alight-cutting portion for cutting light, of the incident light, that haspassed through the photoelectric conversion portion, wherein thelight-cutting portion passes through at least part of the interlayerinsulation film, and the first insulating layer is located between thelight-cutting portion and the semiconductor substrate.
 22. A back-sideillumination image capturing apparatus comprising: a semiconductorsubstrate having a first surface for receiving incident light and asecond surface located on the opposite side as the first surface, andincluding a photoelectric conversion portion, and a gate electrodelocated above the second surface; an interlayer insulation film disposedabove the second surface of the semiconductor substrate; a contact plugconnected to the gate electrode; and a light-cutting portion for cuttinglight, of the incident light, that has passed through the photoelectricconversion portion, wherein part of the interlayer insulation film islocated between the light-cutting portion and the semiconductorsubstrate.
 23. A camera comprising: a back-side illumination imagecapturing apparatus; and a signal processing unit that processes asignal from the image capturing apparatus, wherein the back-sideillumination image capturing apparatus comprises: a semiconductorsubstrate having a first surface for receiving incident light and asecond surface located on the opposite side as the first surface, andincluding a photoelectric conversion portion, and a gate electrodelocated above the second surface; an interlayer insulation film disposedabove the second surface of the semiconductor substrate; a contact plugconnected to the gate electrode; and a light-cutting portion for cuttinglight, of the incident light, that has passed through the photoelectricconversion portion, wherein part of the interlayer insulation film islocated between the light-cutting portion and the semiconductorsubstrate.
 24. The image capturing apparatus according to claim 2,wherein the first insulating layer and the second insulating layer eachhave a layered structure including a silicon oxide film and a siliconnitride film as layers.
 25. The image capturing apparatus according toclaim 1, wherein the semiconductor substrate further includes an elementisolation region in the periphery of the photoelectric conversionportion; and at least part of the light-cutting portion is located overthe element isolation region.
 26. The image capturing apparatusaccording to claim 1, wherein the light-cutting portion is a metal layerembedded in an opening.
 27. The image capturing apparatus according toclaim 1, wherein the light-cutting portion is an air gap formed in anopening.
 28. The image capturing apparatus according to claim 1, furthercomprising: a reflective layer arranged in a position covering thelight-cutting portion.
 29. The image capturing apparatus according toclaim 28, wherein the reflective layer is a part of a wiring patternconnected to the contact plug.
 30. The image capturing apparatusaccording to claim 1, wherein the light-cutting portion reflects thelight that has passed through the photoelectric conversion portion. 31.The image capturing apparatus according to claim 1, wherein thelight-cutting portion has a cylindrical shape extending away from thesecond surface of the semiconductor substrate.
 32. The image capturingapparatus according to claim 1, wherein the light-cutting portion has apillar shape extending away from the second surface of the semiconductorsubstrate.